
package newpackage;


import java.io.IOException  ;
import java.io.InputStream  ;
import java.util.Arrays  ;

/**
24  * a utility class for handling little-endian numbers, which the 80x86 world is
25  * replete with. The methods are all static, and input/output is from/to byte
26  * arrays, or from InputStreams.
27  *
28  *@author Marc Johnson (mjohnson at apache dot org)
29  *@author Andrew Oliver (acoliver at apache dot org)
30  */

public class LittleEndian
implements LittleEndianConsts {

// all methods are static, so an accessible constructor makes no
// sense
/**
38      * Constructor for the LittleEndian object
39      */
private LittleEndian() { }


/**
44      * get a short value from a byte array
45      *
46      *@param data the byte array
47      *@param offset a starting offset into the byte array
48      *@return the short (16-bit) value
49      */

public static short getShort(final byte[] data, final int offset) {
return (short) getNumber(data, offset, SHORT_SIZE);
}
     /**
57      * get an unsigned short value from a byte array
58      *
59      *@param data the byte array
60      *@param offset a starting offset into the byte array
61      *@return the unsigned short (16-bit) value in an integer
62      */
    public static int getUShort(final byte[] data, final int offset) {
         short num = (short) getNumber(data, offset, SHORT_SIZE);
         int retNum;
if (num < 0) {
retNum = ((int) Short.MAX_VALUE + 1) * 2 + (int) num;
} else {
retNum = (int) num;
}
return retNum;
} /**
75     /**
75     /**
76      * get a short array from a byte array.
77      *
78      *@param data Description of the Parameter
79      *@param offset Description of the Parameter
80      *@param size Description of the Parameter
81      *@return The simpleShortArray value
82      */
  public static short[] getSimpleShortArray(final byte[] data, final int offset, final int size) {
short[] results = new short[size];
for (int i = 0; i < size; i++) {
results[i] = getShort(data, offset + 2 + (i * 2));
}
return results;
}
     /**
93      * get a short array from a byte array. The short array is assumed to start
94      * with a word describing the length of the array.
95      *
96      *@param data Description of the Parameter
97      *@param offset Description of the Parameter
98      *@return The shortArray value
99      */
    public static short[] getShortArray(final byte[] data, final int offset) {
        int size = (int) getNumber(data, offset, SHORT_SIZE);
        short[] results = getSimpleShortArray(data, offset, size);
        return results;
    }


    /**
     * get a short value from the beginning of a byte array
     *
     *@param data the byte array
     *@return the short (16-bit) value
     */

    public static short getShort(final byte[] data) {
        return getShort(data, 0);
    }
    /**
     * get an unsigned short value from the beginning of a byte array
     *
     *@param data the byte array
     *@return the unsigned short (16-bit) value in an int
     */
     public static int getUShort(final byte[] data) {
        return getUShort(data, 0);
    }
 /**
     * get an int value from a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@return the int (32-bit) value
     */

    public static int getInt(final byte[] data, final int offset) {
         return (int) getNumber(data, offset, INT_SIZE);
    }

    /**
     * get an int value from the beginning of a byte array
     *
     *@param data the byte array
     *@return the int (32-bit) value
     */

    public static int getInt(final byte[] data) {
        return getInt(data, 0);
     }
    /**
     * get an unsigned int value from a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@return the unsigned int (32-bit) value in a long
     */
public static long getUInt(final byte[] data, final int offset) {
int num = (int) getNumber(data, offset, INT_SIZE);
long retNum;
if (num < 0) {
retNum = ((long) Integer.MAX_VALUE + 1) * 2 + (long) num;
} else {
retNum = (int) num;
}
return retNum;
     }
     /**
     * get an unsigned int value from a byte array
     *
     *@param data the byte array
     *@return the unsigned int (32-bit) value in a long
     */
 public static long getUInt(final byte[] data) {
return getUInt(data,0);
}

/**
     * get a long value from a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@return the long (64-bit) value
     */

    public static long getLong(final byte[] data, final int offset) {
        return getNumber(data, offset, LONG_SIZE);
    }


    /**
     * get a long value from the beginning of a byte array
     *
     *@param data the byte array
     *@return the long (64-bit) value
     */

    public static long getLong(final byte[] data) {
        return getLong(data, 0);
    }


    /**
     * get a double value from a byte array, reads it in little endian format
     * then converts the resulting revolting IEEE 754 (curse them) floating
     * point number to a happy java double
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@return the double (64-bit) value
     */

    public static double getDouble(final byte[] data, final int offset) {
        return Double.longBitsToDouble(getNumber(data, offset, DOUBLE_SIZE));
    }


    /**
     * get a double value from the beginning of a byte array
     *
     *@param data the byte array
     *@return the double (64-bit) value
     */

    public static double getDouble(final byte[] data) {
        return getDouble(data, 0);
    }


    /**
     * put a short value into a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@param value the short (16-bit) value
     */
    public static void putShort(final byte[] data, final int offset,
            final short value) {
        putNumber(data, offset, value, SHORT_SIZE);
    }


    /**
     * put a array of shorts into a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@param value the short array
     */
    public static void putShortArray(final byte[] data, final int offset, final short[] value) {
        putNumber(data, offset, value.length, SHORT_SIZE);
        for (int i = 0; i < value.length; i++) {
            putNumber(data, offset + 2 + (i * 2), value[i], SHORT_SIZE);
        }
    }

    /**
     * put an unsigned short value into a byte array
     *
     * @param data the byte array
     * @param offset a starting offset into the byte array
     * @param value the short (16-bit) value
     *
     * @exception ArrayIndexOutOfBoundsException may be thrown
     */
    public static void putUShort(final byte[] data, final int offset,
                                final int value)
    {
        putNumber(data, offset, value, SHORT_SIZE);
    }

    /**
     * put a short value into beginning of a byte array
     *
     *@param data the byte array
     *@param value the short (16-bit) value
     */

    public static void putShort(final byte[] data, final short value) {
        putShort(data, 0, value);
    }


    /**
     * put an int value into a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@param value the int (32-bit) value
     */

    public static void putInt(final byte[] data, final int offset,
            final int value) {
        putNumber(data, offset, value, INT_SIZE);
    }


    /**
     * put an int value into beginning of a byte array
     *
     *@param data the byte array
     *@param value the int (32-bit) value
     */

    public static void putInt(final byte[] data, final int value) {
        putInt(data, 0, value);
    }


    /**
     * put a long value into a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@param value the long (64-bit) value
     */

    public static void putLong(final byte[] data, final int offset,
            final long value) {
        putNumber(data, offset, value, LONG_SIZE);
    }


    /**
     * put a long value into beginning of a byte array
     *
     *@param data the byte array
     *@param value the long (64-bit) value
     */

    public static void putLong(final byte[] data, final long value) {
        putLong(data, 0, value);
    }


    /**
     * put a double value into a byte array
     *
     *@param data the byte array
     *@param offset a starting offset into the byte array
     *@param value the double (64-bit) value
     */

    public static void putDouble(final byte[] data, final int offset,
            final double value) {
        // Excel likes NaN to be a specific value.
  if (Double.isNaN(value))
            putNumber(data, offset, -276939487313920L, DOUBLE_SIZE);
        else
            putNumber(data, offset, Double.doubleToLongBits(value), DOUBLE_SIZE);
    }


    /**
     * put a double value into beginning of a byte array
     *
     *@param data the byte array
     *@param value the double (64-bit) value
     */

    public static void putDouble(final byte[] data, final double value) {
        putDouble(data, 0, value);
    }


    /**
     * Exception to handle buffer underruns
     *
     *@author Marc Johnson (mjohnson at apache dot org)
     */

    public static class BufferUnderrunException
             extends IOException   {

        /**
         * simple constructor
         */

        BufferUnderrunException() {
            super("buffer underrun");
        }
    }


    /**
     * get a short value from an InputStream
     *
     *@param stream the InputStream from which the short
     * is to be read
     *@return the short (16-bit) value
     *@exception IOException will be propagated back to the caller
     *@exception BufferUnderrunException if the stream cannot provide enough
     * bytes
     */

    public static short readShort(final InputStream   stream)
             throws IOException  , BufferUnderrunException {
        return getShort(readFromStream(stream, SHORT_SIZE));
    }


    /**
     * get an int value from an InputStream
     *
     *@param stream the InputStream from which the int is
     * to be read
     *@return the int (32-bit) value
     *@exception IOException will be propagated back to the caller
     *@exception BufferUnderrunException if the stream cannot provide enough
     * bytes
     */

    public static int readInt(final InputStream   stream)
             throws IOException  , BufferUnderrunException {
        return getInt(readFromStream(stream, INT_SIZE));
    }


    /**
     * get a long value from an InputStream
     *
     *@param stream the InputStream from which the long
     * is to be read
     *@return the long (64-bit) value
     *@exception IOException will be propagated back to the caller
     *@exception BufferUnderrunException if the stream cannot provide enough
     * bytes
     */

    public static long readLong(final InputStream   stream)
             throws IOException  , BufferUnderrunException {
        return getLong(readFromStream(stream, LONG_SIZE));
    }

    /**
     * Read the appropriate number of bytes from the stream and return them to
     * the caller. <p>
     *
     * However, for the purposes of the POI project, this risk is deemed
     * negligible. It is, however, so noted.
     *
     *@param stream the InputStream we're reading from
     *@param size the number of bytes to read; in
     * 99.99% of cases, this will be SHORT_SIZE, INT_SIZE, or LONG_SIZE --
     * but it doesn't have to be.
     *@return the byte array containing the
     * required number of bytes. The array will contain all zero's on end
     * of stream
     *@exception IOException will be propagated back to the caller
     *@exception BufferUnderrunException if the stream cannot provide enough
     * bytes
     */

    public static byte[] readFromStream(final InputStream   stream,
            final int size)
             throws IOException  , BufferUnderrunException {
        byte[] buffer = new byte[size];

        int count = stream.read(buffer);

        if (count == -1) {

            // return a zero-filled buffer
  Arrays.fill(buffer, (byte) 0);
        } else if (count != size) {
            throw new BufferUnderrunException();
        }
        return buffer;
    }


    /**
     * Gets the number attribute of the LittleEndian class
     *
     *@param data Description of the Parameter
     *@param offset Description of the Parameter
     *@param size Description of the Parameter
     *@return The number value
     */
    private static long getNumber(final byte[] data, final int offset,
            final int size) {
        long result = 0;

        for (int j = offset + size - 1; j >= offset; j--) {
            result <<= 8;
            result |= 0xff & data[j];
        }
        return result;
    }


    /**
     * Description of the Method
     *
     *@param data Description of the Parameter
     *@param offset Description of the Parameter
     *@param value Description of the Parameter
     *@param size Description of the Parameter
     */
    private static void putNumber(final byte[] data, final int offset,
            final long value, final int size) {
        int limit = size + offset;
        long v = value;

        for (int j = offset; j < limit; j++) {
            data[j] = (byte) (v & 0xFF);
            v >>= 8;
        }
    }


    /**
     * Convert an 'unsigned' byte to an integer. ie, don't carry across the
     * sign.
     *
     *@param b Description of the Parameter
     *@return Description of the Return Value
     */
    public static int ubyteToInt(byte b) {
        return ((b & 0x80) == 0 ? (int) b : (int) (b & (byte) 0x7f) + 0x80);
    }


    /**
     * get the unsigned value of a byte.
     *
     *@param data the byte array.
     *@param offset a starting offset into the byte array.
     *@return the unsigned value of the byte as a 32 bit integer
     */
    public static int getUnsignedByte(final byte[] data, final int offset) {
        return (int) getNumber(data, offset, BYTE_SIZE);
    }


    /**
     * get the unsigned value of a byte.
     *
     *@param data the byte array
     *@return the unsigned value of the byte as a 32 bit integer
     */
    public static int getUnsignedByte(final byte[] data) {
        return getUnsignedByte(data, 0);
    }


    /**
     * Copy a portion of a byte array
     *
     *@param data the original byte array
     *@param offset Where to start copying from.
     *@param size Number of bytes to copy.
     *@return The byteArray value
     *@throws IndexOutOfBoundsException - if copying would cause access of
     * data outside array bounds.
     */
    public static byte[] getByteArray(final byte[] data, int offset, int size) {
        byte[] copy = new byte[size];
        System.arraycopy(data, offset, copy, 0, size);

        return copy;
     }


  }

